The present invention relates to a method for decontaminating a hollow metal needle intended for sampling and/or dispensing a contaminating liquid, the needle cooperating with electrical wiring means for providing an electric current in the needle for decontaminating and preserving the integrity of the needle with a view to its re-use.
The present invention also relates to a decontamination device which allows the implementation of the above method.
Contaminating liquid is taken to mean any medium which is likely to be processed or manipulated in any method, process or procedure, for example of analysis, but which must be substantially removed or eliminated because, at one time or another it is detrimental to said process, method or procedure, and this being whatever the physical or presentation form of said medium, for example whether it is a material, matter or sample in a liquid or gas or two-phase (liquid + gas) form or alternatively in a powder form, provided that the said medium can be handled as a fluid in particular by aspiration and/or flow reverse.
As a consequence of the previous definition, the terms xe2x80x9ccontaminatedxe2x80x9d and xe2x80x9cdecontaminatedxe2x80x9d mean, respectively, xe2x80x9cbring into contact or introduce a contaminating liquid into or onto an objectxe2x80x9d and xe2x80x9cremove or eliminate the same contaminating liquid from said objectxe2x80x9d.
Ranking highest among the contaminating liquids under consideration by the present invention are biological media, such as samples of fluid or body samplings which can contain or be soiled with various nonpathogenic microorganisms such as viruses, bacteria or other cells. In this case, and for the following description, xe2x80x9ccontaminating liquidxe2x80x9d will mean xe2x80x9cnon-sterile liquidxe2x80x9d and xe2x80x9cdecontaminatedxe2x80x9d will mean xe2x80x9csterilizedxe2x80x9d.
However, the present invention is not limited to sterilization, since many other contaminating media can be considered according to the invention. Thus any nucleic acid material or substance, such as DNA, handled in any molecular biology technique can be the subject of the present invention. This is also the case for any organic medium which it is necessary both to handle and to eliminate at one time or another in any process, for example of chemical or biochemical analysis.
However, the common property of all the contaminating liquids considered by the invention is that they can be destroyed by taking the temperature to a relatively high value, for example exceeding 150xc2x0 C.
The prior art has already proposed methods or devices for efficiently decontaminating hollow metal needles. However, the object of most of the documents of the prior art, such as GB-A-2,211,420, U.S. Pat. No. 5,375,200 or EP-A-0,136,392, is to destroy the needles which have been used.
Such a technique can absolutely not be used with a machine because it considerably increases the cost of using such machines, due to the destruction of very many needles.
Another solution which is particularly evident therefore consists in changing the adapter pieces which are used for the pipettes, it being possible for this technique to be adapted for machines.
In this case, there will be a considerable number of manipulations, which will cause a loss of time on the one hand, and a loss of money on the other.
The latter technique consists in carrying out a washing operation. Most of the current techniques require a large amount of liquid to enable only one hollow needle to be cleaned. On average about 10 ml of cleaning fluid is needed to enable a real decontamination.
However, it has been possible to obtain noticeably better results by other methods, such as that set out in Patent Application EP-A-0,727,228 by the present applicant. It relates to a method for heating a hollow needle consisting essentially of a metal tube whose inside and/or outside have previously been brought into contact with a contaminating medium, according to which an electric current is applied in said needle, which current circulates in the metal wall and depends on the length of said tube, and which resistively dissipates in the latter a heat energy. This method is characterized in that a predetermined amount of electrical energy is supplied in said needle, which is metered as a function of the electrical properties of said tube, on the one hand so as to be enough for the decontamination of the needle both inside and outside, and on the other hand so as to limit the heating and preserve the integrity, including the original shape, of said needle.
The total amount of cleaning fluid is, in this case, considerably less than all the previously described techniques. However, the use of an electrical charge, for example in the needle where the contaminating liquid is present, can cause the crystallization of certain elements of this contaminating liquid, thus harming the quality of the decontamination carried out.
An object of the present invention is therefore to provide a method for decontaminating a hollow needle, but also a device for decontaminating such a hollow needle which requires little cleaning fluid; the method and the device are particularly efficient and economical because they eliminate the contaminated solids (disposable adapter pieces) and reduce the volumes of effluents (contaminated cleaning fluids).
To this end, the present invention relates to a method for decontaminating a hollow metal needle intended for sampling and/or dispensing a contaminating liquid, the needle cooperating with electrical wiring means for providing an electric current in the needle for decontaminating and preserving the integrity of the needle with a view to its re-use, characterized in that it consists:
in injecting a cleaning fluid into the hollow needle having carried out the sampling and/or dispensing of the contaminating liquid,
in applying a heat source to all or part of the cleaning fluid present in said hollow needle, and
in ejecting said contaminating liquid present and all or part of said cleaning fluid.
According to a first embodiment, the injection of the cleaning fluid and the application of the electrical current are done simultaneously.
According to a second embodiment, the injection of the cleaning fluid takes place prior to the application of the heat source.
According to a third embodiment, the application of the heat source takes place prior to the injection of the cleaning fluid.
The electric current vaporizes all or part of the cleaning fluid present in said hollow needle.
According to one particularly advantageous embodiment, the heat source is due to an electric current.
According to one particularly advantageous embodiment of the method, the ejection is carried out under the action of the pressure of said vaporized cleaning fluid.
The present invention also relates to a device for decontaminating a hollow metal needle intended for sampling and/or dispensing a contaminating liquid, the needle cooperating with electrical wiring means for providing an electric current in the needle for decontaminating and preserving the integrity of the needle with a view to its re-use, characterized in that it comprises at least two electrical wires, each wire connecting a source of electrical energy to the needle; the implementation points of said wires, which form electrodes, are distant from each other, but also from the free end of the needle, and in that the other end of said needle cooperates with a means for dispensing a cleaning fluid.
The contaminating liquid, after the sampling and/or the dispensing, is present between the free end of the hollow needle and the electrode which is closest to said free end.
The cleaning fluid, after the sampling and/or the dispensing, is present between the two electrodes.
According to one particular embodiment, an air bubble is present between the contaminating liquid and the cleaning fluid.
According to another embodiment, the cleaning fluid consists of water.
According to yet another embodiment of the present invention, the cleaning fluid consists of a buffer solution.